The invention pertains to an oscillating conveyor comprising an oscillating rail, at least one electromagnet with a coil, and an armature connected to the oscillating rail, which armature can be moved to activate the coil, thus generating an oscillation of the oscillating rail, wherein the coil is part of an oscillator circuit, wherein the oscillation frequency of the oscillator signal of the oscillator circuit depends on the inductance of the coil, which is influenced by the position of the armature relative to the coil.
Oscillating conveyors are used in automated production processes to transport material along rails, e.g., to feed small parts such as structural components. By means of an elliptical shaking movement, the material to be conveyed is guided along a predefined path. The elliptical shaking movement is produced by means of at least one electromagnet. The electromagnet periodically attracts an armature connected to the oscillating rail of the oscillating conveyor, wherein a previously determined restoring force produced by elastic means, typically leaf springs, acts on the oscillating rail and thus on the armature.
The magnitude of the oscillatory amplitude is related to the output of the conveyor, for which reason it is desirable to achieve the largest possible oscillatory amplitude. To achieve this with low energy input, the oscillating conveyor should be operated near its resonance frequency. The problem with this is that, because of the way such a conveyor is built, its oscillations are typically nonlinear, which means that even small deviations from the resonance frequency can lead to pronounced changes in the oscillatory amplitude or even to the collapse of the oscillation.
To excite an oscillating conveyor at a frequency near its resonance frequency, DE 195 31 674 proposes that the inductance of the oscillating conveyor's drive coil, which varies with the timing of the vibrations, be evaluated so that the drive coil can be supplied with drive pulses at the natural frequency of the conveyor. To this end, a digital counter, which is increased at a fixed rate, is read out at intervals determined by a resonator circuit, which comprises the drive coil as a frequency-determining element. The counter status which is read out therefore varies with the timing of the mechanical vibrations of the conveyor, so that, by means of a central unit, a favorable point in the time can be calculated for a drive pulse.